I use the cheapskate version of bar mitts - ATV handwarmers. I'm usually good without them until it gets very cold, like 5F or so. They're not as warm as proper bar mitts, but do their job at blocking that headwind blasting straight outta the north.
I got some much better gloves last winter, and didn't break the handwarmers out at all. Granted, it wasn't all that cold - only a few rides below 0F (for which the new gloves were delightful). Hoping for a more wintry winter this year
